The present invention relates to an electrophotographic photosensitive member, and also a process cartridge and an electrophotographic apparatus including such a photosensitive member.
An electrophotographic photosensitive member basically comprises a photosensitive layer to be charged and photo-exposed to form a latent image thereon, and a support for supporting the photosensitive layer.
The photosensitive layer generates charge carriers on absorbing light energy, and the generated charge carriers are required to quickly move without causing re-combination or being trapped to be extinguished. However, in case where a photosensitive layer is directly formed on a support, the soiling on and the ununiform shape, property and roughness of the support surface are reflected as they are as the irregularity of the photosensitive layer formed thereon, thus resulting in images accompanied with image defects such as white dropout, black spots and density irregularities.
For the above reason and for other purposes, such as improvement of adhesion with the support, protection from electrical break down of the photosensitive layer, and prevention of carrier injection into the photosensitive layer, it has been practiced to dispose an intermediate layer between the support and the photosensitive layer rather than to directly form the photosensitive layer by application on the support.
As materials forming the intermediate layer, polyamides are disclosed in Japanese Laid-Open Patent Application (JP-A) 46-47344, JP-A 52-25638 and JP-A 58-95351; polyesters are disclosed in JP-A 52-20836 and JP-A 54-26738; polyurethanes are disclosed in JP-A 49-10044 and JP-A 53-89435; casein is disclosed in JP-A 55-103556; polypeptide is disclosed in JP-A 53-48523; polyvinyl alcohol is disclosed in JP-A 52-100240; polyvinylpyrrolidone is disclosed in JP-A 48-30936; vinyl acetate-ethylene copolymer is disclosed in JP-A 48-26141; maleic anhydride ester copolymer is disclosed in JP-A 52-10138: and quaternary ammonium salt-containing polymers are disclosed in JP-A 51-126149 and JP-A 56-60448.
These resins are however mostly hygroscopic and the resistivities thereof are remarkably changed depending on environmental humidity. Accordingly, in case where the intermediate layer is formed of such a resin alone, the photosensitive layer is liable to cause an increase in residual potential and changes in electrical properties in low temperature/low humidity environment and high temperature/high humidity environment, so that a sufficient improvement of image defects has not been accomplished.
Accordingly, the use of crosslinked resins as resins having resistivities less affected by environmental changes for the intermediate layer has been proposed. For example, melamine resins are disclosed in JP-A 4-22966, Japanese Patent Publication (JP-B) 4-31576 and JP-B 4-31577; phenolic resin is disclosed in JP-A 3-48256; and epoxy resin is disclosed in JP-A 52-121325. However, a sufficiently low environmental dependence of resistivity has not been achieved by these resins.
On the other hand, as inorganic-type intermediate layers, JP-A 61-94057 has proposed the use of an organometallic compound, and JP-A 2-189559 has disclosed a cured film of zirconium and a silane compound. Such inorganic-type intermediate layers have provided relatively stable electric properties even in environments of high temperature/high humidity and low temperature/low humidity, and a resistivity at a level of stability sufficient to obviate a remarkable increase of residual potential. However, intermediate layers (undercoating layers) disclosed in these references have involved problems that these intermediate layers are of substantially metal oxide films which have poor viscoelasticity, are liable to cause cracks or pores and show inferior adhesion with the support. Moreover, some photosensitive layers have caused problems that the coating liquid thereof is liable to be repelled by such inorganic intermediate layers.
A generic object of the present invention is to provide an electrophotographic photosensitive member with an intermediate layer having solved the above-mentioned problems.
A more specific object of the present invention is to provide an electrophotographic photosensitive member which shows little change in resistivity even under an environmental change from low temperature/low humidity to high temperature/high humidity and is substantially free from residual potential increase.
Another object of the present invention is to provide an electrophotographic photosensitive member with an intermediate layer which shows a good adhesion with the support and the photosensitive layer and can provide stable image qualities on repetitive use.
Further objects of the present invention are to provide a process cartridge and an electrophotographic apparatus including such an electrophotographic photosensitive member.
According to the present invention, there is provided an electrophotographic photosensitive member, comprising: an electroconductive support, and an intermediate layer and a photosensitive layer disposed in this order on the electroconductive support; wherein said intermediate layer comprises a thermosetting resin and an organometallic compound.
The present invention further provides a process cartridge, comprising: the above-mentioned electrophotographic photosensitive member and at least one means selected from the group consisting of charging means, developing means and cleaning means; said electrophotographic photosensitive member and said at least one means being integrally supported and detachably mountable to a main assembly of an electrophotographic apparatus; and also
an electrophotographic apparatus, comprising: an electrophotographic photosensitive member, and charging means, developing means and transfer means respectively disposed opposite to the electrophotographic photosensitive member.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawing.